Collet



March 25, 1947. -E Y 2,417,836

COLLET Filed April 24, 1945 2 Sheets-Sheet l IN VEN TOR.

March 25, 1947.

J. T. OBECNY COLLET Filed April 24, 1943 2 Sheets-Sheet 2 |||||1u FL.INVENTOR. j kizzaecn fiiorney Patented Mar. 25, 1947 UNITED STATESPATENT 1 Claim.

This invention relates to improvements in collets for use particularlyalthough not exclusively in work holders such as are used in machinesfor milling, cutting, gr nding and other work, and partly as set forthin my companion application, Serial Number 405,319, filed August 4, 1941(Patent No. 2,339,800), of which the present application is acontinuation in part.

The primary object of this invention is to provide a collet which willeffectively grip and hold a work piece with sufiicient firmness wellbeyond critical stress, whereby the work piece can be machined or workedwithout deforming or distorting, irrespective of the character of itsmaterial. Another obiect of the invention is to provide a collet whichwill automatically release the work piece when operating force forcontracting the collet ceases. Another object is to provide a collet inwhich an elastic gripping force is applied evenly so as to hold the workpiece firmly without slipping or loosening. Among still further objectsis to provide a collet which is simple and inexpensive in constructionand which is adapted for use in a work holder such as of the typedisclosed in my companion application for patent above identified andwhich lends itself for efiicient and effective use for gang milling,fabricating and any other machine or workingoperation desired.

These and other objects and advantages, to gether with features ofconstruction will appear from the following specification, of which thedrawings form a part- In the drawings, Fig. 1 is a plan, partly brokenaway and in section of a detail portion of a work holder showing myimproved collet in place; Fig. 2 is a side elevation of th collet, whenremoved from the holder which is shown in Fig. 1; Figs. 3 and 4 areplans of slightly modified forms of the collet; Fig. 5 is a plan of thecollet shown in Fig. 1 when constructed with a polygonal socket or bore;Fig. 6 is a side elevation, partly broken away and in section of thestructure shown in Fig. 5; Fig. '7 is a plan of a modified form of myimproved collet for holding a particular type of work piece for straddlemilling; Fig. 8 is a vertical section taken on the line 8-8 of Fig. 7;Fig. 9 is a side elevation of the structure shown in Figs. 7 and 8; Fig.10 is a plan of another modified form of my improved collet, for holdinga particular type of work piece for straddle milling and slotting; Fig.11 is a section taken on the line I l-! I of Fig. 10; Fig. 12 is a sideelevation of the strcture shown in Figs. 10 and 11; Fig. 13is a plan ofa detail portion of a work holder, showing a collet of another modifiedform held therein; Fig. 14 is a front elevation partly in section of thestructure shown in Fig. 13; Fig. 15 is a plan of a detail illustrating awork holder equipped with another alternative construction of collet;Fig. 16 is a plan of a detail illustrating a work holder provided withanother modified form of my improved collet, when held in a chuckopening and provided with means by which the work piece can beaccurately indexed to permit machining its surface with polygonal sides;Fig. 17 is a section of a detail taken approximately on the line indcated by ii in Fig. 16.; Fig. 18 is a front elevation of the structureshown in Fig. 16; and Fig. 19 is a section of detail taken on line l9-llacross the cdllet shown in Fig. 16.

Referring to Fig. 1, there is illustrated a detail,

portion of a holder A, such as is employed for holding a plurality ofwork pieces in suitable out-standing position for machining or workingin a milling machine, grinding machine. shaper, planer or any other typeof machine or work unit. The work holder has socket openings resemblingchucks such as B, of suitable cross sectional shape and dimension toform a seat for receiving and sustaining my improved. collet such as C.As illustrated the chuck seat is of cylindrical shape and the collet isof corresponding shape and of normal diameter correspondingsubstantially with that of the bore of the seat, whereby the collet canwhen desired be freely inserted in or removed from its seat in theholder. The collet is com.- posed of resilient metal, plast c or anyother suitable material. When desired tempered metal may be employed.The body of the collet is provided with a substantially axially disposedwork piece receiving bore D, the wall of which is cyiindrical but may hepolygonal or other suitable shape to grip and restrain the work piecefrom rotating in the collet. Que polygonal form of bore ii! is shown in5, wherein it is hexagonal. The wall of the collet is of any desiredthickness to provide a substantial work piece holding socket of suitablecross sectional dimens on shape. The body of the collet has alongitudinal slit ill which extends transversely across its wall eitherdiametrally as shown or at any angle desired. This slit provides aslight gap between a pair of resilient arcuate 22 and 23, which permitthe collet to contract and engage a work piece E (see Fig. 2). The upperinner corner of the bore terminates at right angle while the endterminates in an inner curved corner 2:3 to conform with different workpieces when the collet is reversed in a chuck.

Th resilient arms 22 and 23 are weakened by a pair of oppositelydisposed inwardly directed slots 24 and 25, traversing the outer wall ofthe collet longitudinally. These slots form weakening cavities and arepreferably spaced a suificient distance from the slit 2! to improve theresiliency of the arms 22 and 23. As shown in Fig. 1, the collet isplaced in the chuck B of the holder as clearly set forth in my companionapplication above identified, with the outer curved surface of one ofits arms 23 facing forwardly to be engaged by the inner end taperingsurface 25 of th hydraulically driven compression plunger 22'. In thisposition the direction of the slit is transverse or normal to the lineof travel of the plunger 21. The plunger is reciprocable in the bore 28of a compression unit, the line of travel of said plunger beingsubstantially transverse to the axis of the collet and its seat. To holdthe collet rigidly from rotating during the compression stroke of thplunger, the collet is engaged by a key or dowel pin 29, which is heldrigidly seated in the body of the holder and engages the collet in oneof its slots such as 25. Hence, the slots 24 and 25 not only weaken thewall of the collet to improve resiliency of its gripping arms but alsoserve to cooperate in holding th collet from rotating in its seat B andto position the collet correctly in the holder.

For use in holding a work piece having a circular bodyor shank ofcomparatively small size in cross section, a socket D of correspondingsmall size as shown in Figs. 3 and 4 is provided in the collet and theweakening slots or cavities 33 and are extended to greater depth and ata rearward converging angle as shown in Fig. 3, or they are connectedwith open enlarged spaces 35 and 35 as shown in Fig. 4 to providegreater resiliency of the compression arms 3'! and 38. For the samepurpose the slit 39 is carried to greater depth diametrally across thebody and its socket D to further weaken the wall of the collet andprovide increased resiliency of the compression arm members.

In operation the arm 22 is held rigidly by the wall of chuck D and thekey 29. During the forward movement of the plunger the cooperatingsurfaces of the plunger and the wall of arm 23 cause the collet to becompressed by a wrapping action around the shank portion of the Workpiece held in the collet, the weakening slots above described and theslit shown in Figs. 3 and 4 equalizing the wrapping tendency andimproving the resiliency of the structure. The work piece is thereforeeffectively engaged and held rigidly by the collet without slipping orloosening while being machined or worked.

In Figs. 7 to 9 inclusive, the collet body F of the general type shownin Fig. 4 is provided with integral upwardly extending work piecesupporting arms 49 and 4| for rigidly holding the head 62 of aparticular type of work piece for straddle milling. In this constructionthe body of the work piece is clamped in the socket D in the body of thecollet as in the construction above described. A pair of inwardly facingcontact points 44 and 45 on the supporting arm members 40 and 4! supportthe head piece while it is being slotted and machined. The slit or gap35! in the body forpermitting contraction of the collet is extendedupwardly through the supporting arms ll] and El. The construction thusset forth is adapted for what is commonly termed straddle milling,grinding or any other machining operation or working.

By slight modification of the construction shown in Figs. 7 to 9inclusive. my improved collet is adapted for straddle milling andslotting operation on the particular type of work shown in Figs. 10 to12 inclusive. In this modification the body G of the collet issubstantially of the type shown in Fig. 3 and the integrallongitudinally extending work supporting arms are spaced apart toprovide a suitable slotting space. In this construction, contact points48 n the several arm members are provided for steadying and supportingthe head 49, while the shank 50 is clamped in the collet and the head ofthe work piece is being straddle milled and slotted.

In Figs. 13 and 14 my improved collet is of that type disclosed in mycompanion application Serial No. 354,597, filed August 28, 1940 (PatentNo. 2,339,799), of which this application is a continuation in part. Inthis type the collet body H is of rectangular shape and contains a workholding socket 55. The body is slit longitudinally at 58 to provide agap between the resilient arms 51 and 58, whereby the collet can becompressed to engage and hold a work piece firmly in its socket.-

One side of the collet including the arm member 5? is secured rigidly byfastening means such as bolts 59 on the supporting walls 60 and 6| inthe body. In this manner a series of the collets can be held by thebody. The collet is adapted to be compressed by the application of aplunger or other compression means against the forward face of thecollet including the resilient arm 58. In this manner the collet arm 58is contracted by a wrap-ping movement to securely engage a work piece inits bore. The end 62 of the arm 58 is shortened to permit freecompression space when a number of collets are assembled in closeposition in the body.

In Fig. 15, the resilient cylindrical collet body I is shown seated inthe corresponding chuck 65 of a work holder and the hydraulicallyactuated reciprocable plunger 66 disposed in the bore ,61, the line oftravel against the side wall of the collet being substantiallytransverse to the axis of the collet. A plurality of sockets 88 areprovided in the collet to grip and hold a plurality of work pieces to bemachined or worked simultaneously. A series of parallel slits 69 instaggered arrangement, from opposite sides of the collet body areprovided, there being a single slit intersecting each socket and all ofthe slits being arranged normal to the beveled face 1!] of the plunger66, so that when the plunger advances the collet is compressed to gripand hold all of the work pieces securely in the collet. The collet bodyalso has a longitudinal weakening channel H in its outer surface toprovide engagement with the key 12 to prevent rotation and to improveflexibility of the collet.

In Figs. 16 to 18 inclusive, my improved collet is shown associated withindexing means by which the work piece which is held by the collet canbe rotated to permit machining or working a number of surfaces whilebeing held in selected rotative positions. For instance, in milling,grinding or other working, the Work piece can be rotated by the colletand adjusted with accuracy to produce a series of finely proportionedand truely finished surfaces. The supporting body J has a series ofchucks, such as '55, in which resilient contractible collet bodies suchas K are seated. Each collet body resembles the general type abovedescribed having a bore 16, being slit at 17 to permit compression, andhaving longitudinal weakening slots 18 to increase resiliency. Thecollet body is prevented from rotating in its chuck 15, by the key 78,which is seated in the body J and engages the collet body in one of theslot 78. Rotatively seated in the bore of the collet body and. on theannular shoulder 19 (see Fig. 17) in the collet body is a collet sleeve80, which is slit longitudinally at 8| to provide a transverse gapcorresponding with the slit 11. The collet sleeve has a socket 82 inwhich the work piece such as L is engaged by simultaneously compressingboth the collet body and said sleeve. The compression of these membersmay be by hydraulically actuated plungers M working simultaneously inbores 83 in the body J, in the manner described in connection with Fig.1, and particularly in my companion application, Serial No. 483,501,filed April 17, 1943, it being understood that a plurality ofhydraulically actuated compression units are provided for gang operationof a number of the work holding collet elements, when applied to any ofthe types of my improved collet above set forth.

In released condition, the collet sleeve 80 can be rotated in a planetransverse to the axis of the collet body by a screw threaded shaft 84which is suitably journaled in the body J and extends forwardly throughthe body and can be revolved by the application of a socket wrench tothe polygonal sided socket 85 (see Fig. 18). The screw thread 86 of theshaft, meshes with a corresponding annular set of threads 81 of a wormgear, in the annular outer surface of the sleeve so that by revolvingthe shaft, the sleeve in which the work piece is seated can be rotatedto adjust and graduate the position of the work piece. When the colletsleeve is regulated as desired in any of its annular positions, thecompression member M is applied by the application of fluid medium undercompression, thus resulting in the simultaneous compression of both thecollet body and its sleeve to engage and hold the work piece therein,rigidly in selected operative position. The indexing scale 88 (see Fig.18), which is associated with the shaft 84 enables the operator todetermine by micrometer adjustment, the angular positions for machiningthe work piece with high precision accuracy. The shaft is shown keyed inplace in the body J by the key bolt 89.

When the compression unit is released into normal inoperative position,the collet sleeve 80 expands and assumes normally released position.Longitudinally disposed spring friction arms 90 (see Fig. 19), seated inrecess grooves 91 and engaging the outer side wall of the collet sleeve,serve normally to frictionally engage and hold the workpiece in thecollet sleeve against unintentional rotation or removal from the sleevewhen the sleeve is at rest or is being rotated by the hand operatedadjusting means. It will be understood that the collet sleeve 80 may beconstructed substantially similar to any of the other collet structuresabove described, excepting that gear driven or other equivalent means,such as described above, is applied thereto.

In accordance with the patent statutes, I have described the principlesof operation of my invention, together with the construction thereofwhich I now consider to represent the best embodiment thereof, but Idesire to have it understood that the structure shown is onlyillustrative and that the invention can be carried out by other meansand applied to uses other than those above set forth, within the scopeof the following claim.

I claim:

A collet for holding a work piece in a support having a cylindricalchuck opening, an immovable key on the inner wall of said opening and aplunger reciprocable laterally to the axis of said opening, said colletcomprising a cylindrical body substantially corresponding with andfreely insertable longitudinally in said chuck opening having alongitudinal socket therein and being bifurcated on one sidelongitudinally from end to end to provide arcuate arms the end of whichare normally separated and at least one of which is resilient andadapted to be contracted by the reciprocable movement of said plunger,and said body having a longitudinal slot in the outer surface of atleast one of said arms to receive and provide fixed engagement with saidkey'when the collet is inserted in said chuck opening, to maintain saidbody with its contractible arm coactively juxtaposed to saidreciprocable plunger.

JOHN T. OBECNY;

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,675,030 Johnson June 26, 19281,895,281 Currie Jan. 24, 1933 1,260,130 Bemis Mar. 19, 1918 1,507,381 Jannell 'Sept. 2, 1924 1,057,605 Windsor et a1 Apr. 1, 1913 2,139,735Derrig Dec. 13, 1938 735,138 Normand Aug. 4, 1903 790,479 Carr et a1 May23, 1905 1,361,198 Strand Dec. '7, 1920 2,162,856 Nitsch June 20, 19392,339,799 O-becny Jan. 25,1944 2,339,800 Obecny Jan. 25,1944 2,228,337Balas Jan. 14, 1941 318,986 Hicks June 2, 1885 696,745 OBrien Apr. 1,1902 1,189,926 Ellis July 4, 1916 2,177,979 Davis Oct. 31, 19392,211,344 Montgomery Aug. 13, 1940

